The present invention relates to steerable catheters and, in particular, it concerns a steering configuration for facilitating steering of a catheter or the like provided with a rigid distal device.
Steerable catheters are well known in medical treatment of the heart. An example is a catheter for use in electro-physiology treatments, manufactured by EP Technologies, Inc., Sunnyvale, Calif., which is also described in U.S. Pat. No. 5,531,686 which is hereby incorporated by reference. FIGS. 2 and 3 of that patent, incorporated herein as FIGS. 2 and 3 of the present application, show the distal end steering portions 160 of a steering mechanism 10 of the catheter. A coiled spring or sleeve 170 defines a central lumen within a steering shaft 30, in which lumen a steering wire 120 is positioned. Protruding from ferrul 190, the distal end 150 of steering wire 120 is welded to a flat lead spring 230 at weld 260. When there is no tension on the steering wire, the lead spring tends to be kept unbent as shown in FIG. 2. While tension is placed on the steering wire 120 by manipulating a controller (not shown), the lead spring 230 and the distal end 150 of the steering wire are bent, thus turning the distal end 160 of the steering shaft 30.
It is often a desirable to couple a device at the distal end of such a catheter. An example is mounting a sensor device for measuring the location of the tip of the catheter, as described in PCT Publication No. WO0010456 which is hereby incorporated by reference. Such a device is formed as a solid cylinder, so that the leading spring and steering wire cannot extend through the device. As a result, such devices are typically attached as an extension to the end of the steering mechanism described, for example, by welding to the end of the catheter.
Addition of a rigid device to the end of a steerable catheter as described generates a significant degradation of the steerability of the catheter. Specifically, with reference to FIG. 4, it will be noted that the rigid device 1000 in such an arrangement always assumes a position corresponding to a straight non-steerable extrapolation of the direction in which the end portion 260 of lead spring 230 is directed. This interferes considerably with the maneuverability of the overall structure.
There is therefore a need for a steering configuration for facilitating steering of a catheter or the like provided with a rigid distal device which would enable the rigid device to be steered beyond the angle of the distal portion of the lead spring.
The present invention is a steering configuration for facilitating steering of a catheter or the like provided with a rigid distal device.
According to the teachings of the present invention there is provided, a steering configuration for facilitating steering of a catheter or the like provided with a rigid distal device, the steering configuration comprising: (a) a flexible support element having a proximal end and a distal end; (b) a rigid device attached to the distal end of the flexible support element; and (c) at least one elongated,flexible control element configured such that tension applied to the control element causes flexing of the flexible support element, wherein the control element is directly attached to the rigid device.
According to a further feature of the present invention, the rigid device is attached to the distal end of the flexible support at a first attachment region, and the control element is attached to the rigid device at a second attachment region, the second attachment region being removed from the first attachment region in such a manner that tension applied to the control element applies a turning moment between the rigid device and the flexible support in the first attachment region.
According to a further feature of the present invention, the flexible support is implemented as a spring element biased to return to a substantially straight position.
According to a further feature of the present invention, the flexible support is implemented as a leaf spring element.
According to a further feature of the present invention, the rigid device is a sensor.